mobility aids?

hiya im a young person who has been suffering from chronic pain and suspected authorities and suspected pots. I've had pain in my joints for six almost seven years and weakness and fatigue in my muscles as well as pain for almost three years. My symptoms have gotten much much worse over the past two years and now I'm often in too much pain to simply live my life. I've been considering a mobility aid (forearm crutches or a cane) for a good while now but as i am A) under 18 and live with my parents who have been firm believers my whole life that this will "be gone by next year" every year and B) battling with doctors to get them to believe me and that its not just growth hormones, i am unsure about how to go about getting one. I live in scotland so I'm not sure if there's any rules but do i need to ask my doctor or can i just find a way around that? All doctors (for six whole years!) have told me that "it'll go away next year don't worry!" and then surprise surprise it doesn't :l I'm young and just want to find something that'll help me live my life close enough to the rest of my peers. But i'm constantly being forced to question myself and if I'm really disabled enough due to everyone around me gaslighting me. I really don't know what to do.